Extruded ribbon of fire clay



July 16, 1963 w. B. YERRICK 3,097,405

. EXTRUDED RIBBON OF FIRE CLAY Filed Nov. 22, 1960 Fig.2.

United States Patent 3,097,405 EXTRUDED RIBBON OF FIRE CLAY William B.Yerrick, Oakmont, Pa., assignor to Kittanning Brick Company, Reesdale,Pa., a corporation of Pennsylvania Filed Nov. 22, 1960, Ser. No. 70,9598 Claims. (Cl. 22-147) This invention relates to improvements in theteeming of metal ingots and relates in particular to an improved methodof efiecting a seal between ingot molds and hottop molds during pouringor teeming of steel ingots.

In the manufacture of wrought metal products and particularly wroughtsteel, it is customary to pour or teem molten metal from a ladle intoingot molds which are thick-walled iron castings of widely varyingshapes and sizes. The metal or steel freezes or solidifies in thesemolds to form ingots which are subsequently stripped or removed from themolds and are bloomed or hot rolled and otherwise mechanically deformedto form wrought metal products. When molten metal such as molten steelsolidifies or freezes, it is known to contract and lose some of thedimensional volume it occupies while in the liquid state. Since suchfreezing or solidification is not instantaneous, but occurs over aperiod of time and the ingot does not contract uniformly, but generallysolidifies trom the bottom up and from the outside in so that any lossof dimension by the bottom of the ingot is compensated for immediatelyby the still molten metal above flowing downwardly to fill any void. Atthe top of the ingot, however, where there is no compensating moltenmetal to fill the void, there occurs what is known as pipe which is acone-shaped cavity which forms in the top portion of the ingot duringthe solidification of the metal. The walls of such pipe generallyoxidize and will not weld during subsequent rolling. Consequently, amajor portion of the ingot must be cropped or removed and productivityor yield associated with the quantity of metal poured is greatlydiminished, particularly where big end up molds which have a largercasting cavity at the top than the bottom, are employed. The undesirableellects of pipe are generally minimized by employing what is known as ahot-top on top of the ingot. In this practice, a mold of smaller insidedimensional area is positioned above the ingot mold so that afterteeming there is a rel-atively small reservoir of molten metal above theingot mold and upon freezing and contraction of the ingot, molten met-a1may flow from the hot-top mold to replenish loss of volume in the ingotmold and avoid the formation of pipe in the ingot proper. The hot-topitself is that smaller volume of metal remaining in the hot-top moldafter freezing which exhibits considerable pipe, but which may becropped from the ingot proper with very little loss of metal orreduction in yield. Hot-top molds vary in design and method of seatingabove the ingot mold, however, a common practice is to employ a hot-topmold that will seat directly onto the top surface of the ingot mold.Since both molds are generally made from metal castings, a sealingmaterial must be employed to prevent the molten steel from penetratingfrom between the molds. Prior known sealing materials include what isknown in the trade as asbestos rope, however, such rope is relativelyexpensive and is not entirely satisfactory in preventing the penetrationof the molten metal. Such asbestos rope is not readily compressible anddoes not flow into the imperfections and warpage norm-ally found on boththe top surface of the ingot mold and the bottom of the hot-top mold sothat some steel usually penetrates between the molds during teeming whenasbestos rope is employed. Prior attempts to employ cements or clay as asealing material have been relatively unsuccessful because it isdifficult to trowel on such a material evenly so that the molten steel3,097,405. Patented July 16, 1963 will not penetrate between the molds.Additionally, it is necessary to add considerable water to a given claymixture to provide the plasticity required to enable one to trowel iton. It is important to minimize the water content, since high watercontent clay mixture tend to slump and shrink when dried, which causescracks and voids to occur in the seal. Where high water content claysare employed, some residual water remains even after the clay has beenpurposely dried by heating. Such residual water is known to boil duringteeming and is known to cause excessive oxygen pick-up by the risingmolten metal which, in turn, causes numerous oxide inclusions to occurin the steel. Also, high water content troweled-on clays tend to crumblewhen dried prior to teeming. Uneven applications of fire clay, resultingfrom troweling on such materials or cracking caused by excessive Watercontent, not only result in metal penetration between the molds but,also, cause dirty steel, which is a term applied to a steel whichcontains numerous large non-metallic inclusions (in this case, claywhich has fallen into the mold cavity during or prior to teeming).

A similar problem also exists where a big end down ingot mold isemployed. A hot-top is not generally used where this type of teeming isutilized, since the ingot freezes from the top down; however, a sealsimilar to that employed between a hot-top mold and an ingot mold mustbe effected between the ingot mold and the stool upon which it sits toprevent the molten metal from flowing between these two members duringteeming.

It has now been found that by employing the extruded unfired fire clayrope or ribbon of the present invention between a hot-top mold and aningot mold, or between an ingot mold and a stool, a strong andcontinuous seal may be effected that may be readily dried, is simple toapply, and which does not slump or shrink during teeming.

It is,.accordingly, the object of the present invention to provide amethod whereby fire clay may be employed to effect a seal between aningot mold and a hot-top mold during teeming that will not slump,shrink, crack or leave voids, but which will form a strong uniform andcontinuous seal.

It is a further object of the present invention to provide a methodwhereby extruded fire clay may be employed to effect a seal between anymold and any second member where such a seal is required to preventmolten metal from penetrating from the casting cavity during teeming.

It is also an object of the present invention to provide fire clay in aform that will enable one to place it about the top edge or flange of aningot mold with greater ease and economy of application than bytroweliug, so that when the hot-top mold is set on top of the ingotmold, it will form a uniform clay seal therebetween that, after dryingand upon teeming, will form a uniform and effective seal between saidmolds.

Other objects and advantageous features will be obvious from thefollowing specification and drawings where- 1n:

FIGURE 1 is a view in elevation of an extruded fire clay rope which is apreferred embodiment of the present invention;

FIG. 2 is a cross-sectional view of the extruded rope of FIG. 1 shown asseated on a segment of ingot mold wall;

FIG. 3 is a partial cross-sectional view showing the juncture of oneWall of a hot-top mold seated on a portion of one wall of an ingot mold;and

FIG. 4 is a cross-sectional view of a fire clay rope that constitutesanother embodiment of the present invention.

In general, the present invention relates to an extruded fire clay ropeor ribbon of low water content and relates in particular to such a ropeor ribbon that is formed into a substantially oval shape, at least oneelongated side of said ribbon having an indentation therein. The presentinvention also relates to the method of teeming ingots wherein theaforementioned fire clay ribbon is seated on the top surface of an ingotmold so as to enurely encompass the ingot mold casting cavity, a hot-topmold is seated on the top of said ingot mold and fire clay rope so thatthe rope deforms and flows under the weight of the hot-top mold to forma uniform. seal between said molds, heat is applied to the said fireclay rope or ribbon to drive off substantially all the moisture in theclay so that the fire clay will efiect a uniform seal between the moldsthat will prevent the molten metal from penetrating between the moldsduring teeming.

In making extrusions, such as are employed in the method of the presentinvention, various types of clay and other materials are broughttogether in order to attain the most desirable plastic properties thatwill enable the material to be extruded and yet retain sufiicient greenstrength or the ability to retain its shape after being dried. The fireclay rope of the present invention is manufactured from naturaloccurring earthy clays re sulting from the decomposition of rocks,chiefly feldspathic and containing hydrated alumina-silicates. Manytypes of clay are suitable for the manufacture of this product,including plastic surface clays, plastic shales and most fire clays. Forthe purposes of the present invention, all these materials are referredto as fire clays. The preferred materials are the more plastic fireclays of the siliceous, kaolinitic or aluminous type with a minimumpyrometric cone equivalent of Cone 16 (A.S.T.M. designation forrefractories specification C 2456). Such mixtures and blends of clayspreferably will fall within the following calculated approximatechemical analyses after ignition: 1

Percent by weight 'z 4040 A1 20-50 F6203 .5-5 CaO .5-5 MgO .0-5 Ti0 .0-5Alkalies .5-5

The term, alkalies, as applied to the above analyses, includes any andall of the naturally occurring alkali or alkaline earth metal compoundsfound in clay deposits. In the gnited state, such materials aregenerally regarded as the oxides of sodium and potassium since thesematerials generally account for nearly all of the caustic materialspresent. It is common practice in calculated analyses to regard thisrange as the M120 and or K20 content.

Plasticity is that property which enables a clay to be distorted withoutrupture and to retain this distorted shape after the force has beenremoved. The plasticity, strength, workability and shrinkage of a clayis greatly affected by the size and shape of the clay particles.Therefore, the clay to be used must be carefully ground and. screened todevelop a particle size range which will develop good plasticity andwill dry with a minimum amount of shrinkage or cracking. The particlesize range is as follows:

Percent Tyler standard mesh No. 8 to 28 inclusive 5-50 Tyler standardmesh No. 28 to 65 inclusive 5-40 Tyler standard mesh No. 65 to 100inclusive 10 30 Tyler standard mesh N0. 100 to micron size 5-20 Heaicedto about 1000" C. to drive off water and volatile.

materia The water serves to develop plasticity while the binder aidsplasticity, improves the extrusion characteristics and serves to developadditional strength of the material when it dries. The water content iscritical for a given clay mix and must be carefully controlled to insuregood extrusion, satisfactory handling characteristics, and properplasticity.

The tempered clay mixture is then fed to a commercial extrusion machinewhich first shreds the material into small particles. These particlessubsequently pass into a vacuum chamber and are then reconsolidated byan auger which forces the plastic clay mix into a mass and extrudes itthrough a suitable die.

The extruded clay rope will have a water content of from about 55-20%,by weight, and when placed on the top of an ingot mold and a hot-topmold is seated on top of the rope, the fire clay rope will deformsufficiently to fill all voids and imperfections occurring in theadjacent surfaces of both molds, but at the same time, will support thehot-top mold even though the mold may weigh up to a couple thousandpounds, so that the two molds will not come together and cause the clayto flow from between the molds, but the hot-top mold is entirelysupported by the clay rope. The rope must, of course, be of such alength, and be so positioned, as to extend entirely around the castingcavity of the ingot mold and as to contact uniformly the bottom surfaceof the hot-top mold when it is seated on the ingot mold.

Although the water content of the extruded fire clay depends on themechanical and physical properties of the specific mixture beingemployed so that the water content may vary from 8% to 20%, by weight,from 5% to 10% less water is needed for the extruded rope than for acomparable mix prepared for application with a trowel and, consequently,boiling is minimized. For example, a clay mixture which will require l7%water to trowel, may require only about 10% water to extrude. Thepreferred fire clay rope of the present invention will contain from 10%to 15%, by weight, water, which is less than that required to trowel onsuch mixtures.

Although clay rope of rectangular, square and round cross-sectionalshapes have been successfully employed; the preferred shape is thesubstantially indented oval shape, such as is shown by FIG. 2 of thedrawings. A rectangular-shaped rope does not readily flow or give, butinstead tends to retain its extruded shape when dried, thus increasingthe possibility of metal penetration during teeming in areas-where themolds are slightly warped. Round shapes also may fail to flowsuificiently, and when dried, may permit metal penetration.

As shown by the drawings, clay rope 11 is extruded in the indented ovalshape shown by FIGS. 1 and '2, however, when seated as shown in FIGS. 2and 3 on the upper surface 13 of the ingot mold 15 and a hot-top mold 17is seated on the rope 11 as shown by FIG. 3, rope 11 will flow andbulge.

It is to be noted that the rope 11 flows and bulges as shown at 19', butstill supports the hot-top mold 17 and does not permit it to contact theingot mold 15. In this manner, all defects and warpage imperfections ofboth molds are filled and a uniformly continuous seal is effected. Thepreferred cross-sectional configuration may be that of a double circlesuch as shown by FIG. 4, or may be that of an oval shape with a singleindentation such .as is shown by FIG. 2. Either of the elongated sidesof the oval may be seated on the upper surface of the ingot mold toobtain optimum results.

The next step in the method of the present invention is to dry the clay.This has been accomplished effectively by applying the clay rope andpositioning the hot-top mold while the ingot is hot, such heat comingfrom the preceding teeming, or the mold and/or the hotat-op mold may bespecially heated prior to assembly. Also, the rope has been successfullydried by inserting a flaming torch into the casting cavity and/ or byplaying such a flame around the outside surface of the molds. Any sourceof heat may be employed so long as it raises the temperature of the ropesufliciently to drive ofi the water content. A temperature of from 300F. to 1000 F. is usually suiticient. It is to be noted that contrary toprior attempts to employ fire clay to effiect the seal, the extrudedribbon will not shrink materially during drying, does not crumble orleave voids, and the bulges such as shown at 19 in FIG. 3, do not fallor crumble into the mold during teeming so as to effect dirty steel.

Although the temperature of molten steel is substantially above thatrequired for firing many types of fine clay to effect a vitreous mass,the time at such temperatures during ordinary teeming is insufficient tocause the clay to vitrify. As a result, when the molds are stripped fromthe ingot, the clay seal may be easily removed in that the dried claywill readily part from the metallic surfaces.

Although the ideal dimensions of the fire clay rope of the presentinvention depend on the dimensions of the ingot mold and hot-top moldbeing employed, it has been found that for most purposes, two to 1"circles overlapped, provide an ideal shaped rope that will afiiord thedesired flow and bulging, while resisting complete collapse for mostteeming operations. In any event, a rope dimension of less than /2 inwidth and A in height would not be desirable in that a smaller dimensionthan this could not fill the imperfections and =warpage spaces occurringbetween the surface of the molds.

In the use of asbestos rope, a shelf of molten metal be tween the ingotmold and the hot-top mold frequently forms during teeming. Such a shelfis caused and forms Where the asbestos rope does not extend to theinside edge of the ingot mold or, may be due to improper seating of theasbestos rope or movement of the rope While seating the hot-top mold.Such a shelf causes damage to the ingot in that when the freezing ingotcontracts, its entire weight is placed on the aforementioned shelf. Theresultant stress concentrations frequently causes cracking of the ingotcommencing in the vicinity of the shelf.

It is seen by FIG. 3 of the present drawings that the flow of a rope ofthe preferred shape eifects a bulge such as shown at 19 that usuallyextends beyond the edge 21 of the ingot mold so that no shelf can beformed.

As has been mentioned above, in big end down ingot teeming, the big orgreater diameter end of the ingot is seated on a stool or bottom memberand a similar seal is required for between the ingot mold and the stool.'Ihe fire clay rope of the present invention possesses all theadvantages for this application as it does for sealing the area betweenthe hot-top mold and ingot mold during teeming.

It should be noted that the fire clay rope and method of the presentinvention are equally applicable to all ingot molds regardless of theirshape. For example, the fire clay rope may be laid along the top surfaceof octagonal, square or hexagonal-shaped molds, as well as round molds,since the clay rope may be bent or formed to conform to the shape of theingot and hot-top molds.

It also is noted that the present fire clay rope may be slightlyoverlapped and joined and welded by hand to completely circumvent thecasting cavity.

I claim:

1. In the method of teeming ingots wherein a hot-top mold is set on topof an ingot mold and molten metal is cast into the casting cavities ofsaid. molds until the molten metal rises into the hottop mold, theimprovement comprising, seating an extruded elongated rope of of undriedand unfired fire clay continuously about the top surface of said ingotmold so as to completely circumvent said casting cavity, seating saidhot-top mold on top of said ingot mold and fire clay rope so as to flowsaid extruded fire clay between said molds to form a uniform sealtherebetween, drying said fire clay and teeming.

2. In the method of teeming ingots wherein a hot-top mold is set on topof an ingot mold and molten metal is cast into the casting cavities ofsaid molds until the,

molten metal rises into the hot-top mold, the improvement of extrudingan elongated rope of unfired and undried fire clay that contains fromabout 8% to 20%, by weight, water, into a substantially oval shape, atleast one elongated side of which is formed with an indentation therein,seating said rope on the top surface of said ingot mold on at least oneelongated side of said ovalshaped extruded fire clay rope so that saidrope completely encompases the casting cavity of said ingot mold,seating said hot-top mold on top of said ingot mold and fire clay ropeso as to flow said extruded fire clay between said molds to form auniform seal therebetween, drying said fire clay and teeming.

3. In the method of teeming ingots wherein a hot-top mold is set on topof an ingot mold and molten metal is cast into the casting cavities ofsaid molds until the molten metal rises into the hot-top mold, theimprovement of extruding an elongated rope of unfired and rundried fireclay of the following dry weight chemical analysis after ignition:

Percent by Weight 40-70 20-40 Si0 A1203 F8203 .5-5 CaO .5-5 MgO Up to 5TiO Up to 5 Alkalies .5-5

that contains from about 8% to 20%, by Weight, water, and seating saidrope continuously about the top surface of said ingot mold so as tocompletely circumvent the casting cavity of said mold, seating saidhot-top mold on top of said ingot mold and fire clay rope so as to flowsaid extruded fire clay between said molds, so as to form a uniform sealbetween said molds, drying said fire clay and teeming.

4. In the method of teeming ingots wherein a hot-top mold is set on topof an ingot mold and molten metal is cast into the casting cavities ofsaid molds until the molten metal rises into the hot-top mold, theimprovement of extruding an elongated rope of unfired and undried fireclay of the following dry weight chemical analysis after ignition:

stantially oval shape, at least one elongated side of which is formedWith an indentation therein, seating said rope on the top surface ofsaid ingot mold on at least one elongated side of said oval shapedextruded fire clay rope so that said rope completely encompases thecasting cavity of said ingot mold, seating said bot-top mold on top ofsaid ingot mold and fire clay rope so as to fiow said extruded fire claybetween said molds to form a uniform seal therebetween, drying said fireclay and teeming.

5. In the method of teeming ingots wherein a hot top mold is set on topof an ingot mold and molten metal is cast into the casting cavities ofsaid molds until the molten metal rises into the hot-top mold, theimprovement comprising, extruding an elongated rope of unfired and un- 7dried fire clay of the. following calculated chemical analyses afterignition:

Percent by weight Si 40-70 A1 0 20-40 F203 .5-5 CaO .5-5 M g0 Up to 5TiO Up to 5 Alkalies .5-5 Water 8-20 Binder Up to 5 seating said ropecontinuously about the top surface of said ingot mold seating saidhot-top mold on top of said ingot mold and fire clay rope so as to fiowsaid extruded fire clay between said molds and form a uniform sealtherebetween, drying said fire clay and teeming.

6. In the method of teeming ingots wherein a hot-top mold is set on topof an ingot mold and molten metal is cast into the casting cavities ofsaid molds until the molten metal rises into the hot-top mold, theimprovement comprising, extruding an elongated rope of unfired andundried fires clay of the following calculated chemical analysis afterignition:

Percent by weight Si0 40-70 A1 0 20-40 F203 -5 5 CaO .5- 5 MgO Up to 5TiO Up to 5 Alkalies .5- 5 Water 8-20 Binder Up to 5 At least onematerial selected from the group consisting of 12-20 mesh silica sandand 12-20 mesh grog 5-20 seating said rope continuously about the topsurface of said ingot mold, seating said hot-top mold on top of saidingotmold and fire clay rope so as to flow said extruded.

fire clay between said molds and form a uniform seal therebetween,drying said fire clay and teeming.

7. In "a method of casting molten metal into a mold wherein a seal iseffected between said mold and a stool to. prevent said molten metalfrom penetrating between said mold and said stool, the improvementcomprising seating an extruded elongated rope of undried and unfiredfire clay continuously about the top surface of said stool so as tocompletely encompasse the casting cavity of said mold when seated onsaid stool, seating said mold on said stool and fire clay rope so as toflow said extruded fire clay between said mold and stool to form auniform seal therebetween, drying said fire clay and castmg.

8. In the method of casting molten metal into a mold wherein a seal iseffected between said mold and a stool to prevent said molten metal frompenetnating between said mold and said stool, the improvement ofextruding an elongated rope of unfired and undried fire clay thatcontains from about 10% to 15%, by weight, water, into a substantiallyoval shape, at least one elongated side of which is formed with anindentation therein, seating,

said rope on the top surface of said stool on at least one elongatedside of said oval-shaped extruded fire clay rope so that said ropecompletely encompasses the casting,

cavity of said mold when seated on said stool, seating said mold on saidstool and fire clay rope so as to flow said extruded fire clay betweensaid mold and stool to form a uniform seal therebetween, drying saidfire clay and casting.

References Cited in the file of this patent UNITED STATES PATENTS1,332,905 Lindemuth Mar. 9, 1920 2,049,981 'Iurner Aug. 4, 19362,099,342 Lemmerman Nov. 16, 1937 2,863,192 Kauffman Dec. 9, 1958

1. IN THE METHOD OF TEEMING INGOTS WHEREIN A HOT-TOP MOLD IS SET ON TOPOF AN INGOT MOLD AND MOLTEN METAL IS CAST INTO THE CASTING CAVITIES OFSAID MOLDS UNTIL THE MOLTEN METAL RISES INTO THE HOT-TOP MOLD, THEIMPROVEMENT COMPRISING, SEATING AN EXTRUDED ELONGATED ROPE OF OF UNDRIEDAND UNFIRED FIRE CLAY CONTINUOUSLY ABOUT THE TOP SURFACE OF SAID INGOTMOLD SO AS TO COMPLETELY CIRCUMVENT SAID CASTING CAVITY, SEATING SAIDHOT-TOP MOLD ON TOP OF SAID INGOT MOLD AND FIRE CLAY ROPE SO AS TO FLOWSAID EXTRUDED FIRE CLAY BETWEEN SAID MOLDS TO FORM A UNIFORM SEALTHEREBETWEEN, DRYING SAID FIRE CLAY AND TEEMING.